1. Field of the Invention
The present invention relates generally to a tape cassette having means for locking reels thereof and, more particularly, is directed to a tape reel lock and release device of a tape cassette which can, upon non-use of tape cassette, prevent tape reels from being rotated unintentionally by engaging members formed on a reel locking member with gear portions of the tape reels.
2. Description of the Prior Art
In a tape cassette, when tape reels rotatably provided within cassette halves are rotated upon non-use, a magnetic tape wound around the tape reels is slackened. The assignee of the present application has previously proposed a tape reel lock and release device which can prevent tape reels from being rotated inadvertently. This previously-proposed tape reel lock and release device is disclosed, for example, in Japanese Patent Application No. 62-78747.
An enlarged, plan view forming FIG. 1 illustrates an example of such tape reel lock and release device. As Fig. 1 shows, a reel locking member 4 having a pair of engaging members 3, 3 to be engaged with gear portions 2 of a tape reel 1 is spring-biased toward the tape reels 1 by a spring 9. Hinge portions 5 and 6 are each formed on the base portions and intermediate portions of the pair of engaging members 3 and 3. Further, a central rib 7 is protrusively formed from a cassette half 8 at the position in which the engaging members 3 are engaged with the gear portions 2. This central rib 7 extends the engaging members 3, 3 toward the tape reels 1, causing the tape reels 1 and the engaging members 3 to be engaged with each other.
In this prior art tape reel lock and release device, however, the gear portions 2 and the engaging members 3 can be engaged positively to some extent. In this engagement, the engaging members 3, 3 push the tape reels 1 in the direction shown by arrows a in FIG. 1 such that the tape reels 1 are moved toward the tape eject opening side. There is then a risk that the magnetic tape (not shown) wound around the tape reels 1 will be slackened. If the magnetic tape is slackened as described above, when the tape cassette, for example, is ejected from a cassette loading portion of a video camera or the like, its lid portion will bite the magnetic tape.
Therefore, as shown in FIGS. 2 to 4, the configuration of the central rib 7 which extends the engaging members 3, 3 is modified, whereby while the reel locking member 4 is moved from its lock-released state shown in FIG. 2 to its locking completion state shown in FIG. 4, the engaging members 3, 3 come in contact with the central rib 7 as shown in FIG. 3, thus the engaging members 3, 3 being extended to be engaged with the gear portions 2. Thereafter, the reel locking member 4 is slid further such that the engaging members 3, 3 rotate the tape reels 1 in the tape slack absorbing direction shown by arrows b in FIG. 4. Thus, upon locking, the tape slack can be absorbed.
When the reel locking member 4 is slid relative to the central rib 7 as described above, the pair of engaging members 3 and 3 formed at the top of the reel locking member 4 are provided with hinge portions 6 and 6 at their intermediate portions so that the engaging members 3 and 3 can be displaced at their hinge portions 6 and 6. Thus, when the engaging members 3 rotate the tape reels 1 in the tape slack absorbing directions b, the engaging members 3 are flexed at their hinge portions 6 formed at the intermediate positions thereof, thus the tape reels 1 cannot be rotated sufficiently in the tape slack absorbing direction b.
Further, when the engaging members 3 rotate the tape reels 1 in the tape slack absorbing direction b, the engaging members 3 push the tape reels 1 in the direction shown by arrows c in FIG. 4 with the result that their pushing forces weaken, swinging the engaging members 3 in the direction shown by arrows e in FIG. 5. There is then a risk that the engaging members 3 will come off from the gear portions 2 of the tape reels 1. Consequently, the tape reels 1 cannot be sufficiently prevented from being inadvertently rotated by the above-mentioned locking member 4.
Furthermore, since the hinge portions 6 are formed on the intermediate portions of the engaging members 3, when the engaging members 3 are handled as assembly parts and/or attached to the tape cassette or the engaging members 3 are left for a long period of time under the reel lock releasing condition after they are incorporated in the tape cassette, the engaging members 3 are frequently deformed so that the tape reels 1 cannot be positively prevented from being rotated.